1
$\begingroup$

I know this question sounds lame, but the book I am following doesn't use the answer I expect and it has been using a similar notations everywhere else which has confused me.

I think Q[Any tensor] transpose Q can be written as Q(im)Q(mj), but the book has written Q(im)Q(jm) which, in my opinion, doesn't even satisfy the condition of matrix multiplication, so it should be wrong.

enter image description here

Improve this question
$\endgroup$
1

2 Answers 2

Reset to default
8
$\begingroup$

$(Q\cdot Q)_{ij}=Q_{im}Q_{mj}$

$(Q^T\cdot Q)_{ij}=(Q^T)_{im}Q_{mj}=Q_{mi}Q_{mj}$

where we use that $(Q^T)_{im}=Q_{mi}$

Improve this answer
$\endgroup$
1
$\begingroup$

What you suggest is Q times Q, not Q transpose times Q. Check the definition of matrix multiplication.

Improve this answer
$\endgroup$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.